Safety control valve for propane catalytic heater

ABSTRACT

A safety control valve for propane catalytic heaters is provided which meters a desired amount of fuel to the catalytic heater head when the heater is operating but which prevents fuel flow when the heater is not operating. The valve includes a casing in which a control shaft is rotatably mounted, the casing having a fuel inlet port and a fuel outlet port. An orifice plate is mounted on the shaft for rotation adjacent the outlet port and is provided with a plurality of different sized openings which are registrable with the fuel outlet port to regulate the amount of fuel being supplied to the heater. The shaft extends rotatably through a plate provided with position-indicating pockets which successively receive a ball bearing positioned within an opening in another plate which rotates with the shaft. The bearing is resiliently biased toward the position-indicating pockets by a presser plate which also includes an axially extending tang. The fuel inlet port is provided by a bore extending generally perpendicularly to the shaft, and a rod is slidably mounted within the bore and resiliently biased toward the shaft. A valve closure member is resiliently biased against a valve seat surrounding the inlet bore to close the bore, and when the shaft is rotated to the start position the tang engages the rod and pushes it against the valve closure member to open the inlet port. An electromagnetic power head is operatively connected to the valve closure member for holding the closure member in an open position when the catalytic heater is operating.

United States Patent [1 1 Gruver, Jr.

[ June 26, 1973 SAFETY CONTROL VALVE FOR PROPANE CATALYTIC HEATER [75]Inventor: Floyd 0. Gruver, Jr., Wichita, Kans. [73] Assignee: TheColeman Company, lnc.,

Wichita, Kans.

[22] Filed: July 6, 1971 [21] Appl. No.: 159,870

[52] US. Cl 137/66, 251/206, 251/297, 431/80 [51] Int. Cl. F23d 5/16,Fl6k 5/10 [58] Field of Search 137/65, 66, 209; 431/79, 80, 53; 251/207,297, 208, 206

[56] References Cited UNITED STATES PATENTS 3,446,227 5/1969 Grayson137/66 3,550,603 12/1970 Schueler... 137/66 2,455,625 12/1948 Trantin251/207 3,381,696 5/1968 Krueger 137/66 Primary ExaminerWillaim R. ClineAtt0rneyDawson, Tilton, Fallon & Lungmus [57] ABSTRACT A safety controlvalve for propane catalytic heaters is provided which meters a desiredamount of fuel tothe catalytic heater head when the heater is operatingbut which prevents fuel flow when the heater is not operating. The valveincludes a casing in which a control shaft is rotatably mounted, thecasing having a fuel inlet port and a fuel outlet port. An orifice plateis mounted on the shaft for rotation adjacent the outlet port and isprovided with a plurality of different sized openings which areregistrable with the fuel outlet port to regulate the amount of fuelbeing supplied to the heater. The shaft extends rotatably through aplate provided with position-indicating pockets which successivelyreceive a ball bearing positioned within an opening in another platewhich rotates with the shaft. The bearing is resiliently biased towardthe position-indicating pockets by a presser plate which also includesan axially extending tang. The fuel inlet port is provided by a boreextending generally perpendicularly to the shaft, and a rod is slidablymounted within the bore and resiliently biased toward the shaft. A valveclosure member is resiliently biased against a valve seat surroundingthe inlet bore to close the bore, and when the shaft is r0- tated to thestart position the tang engages the rod and pushes it against the valveclosure member to open the inlet port. An electromagnetic power head isoperatively connected to the valve closure member for holding theclosure member in an open position when the catalytic heater isoperating.

9 Claims, 14 Drawing Figures PATEMED JUNE 6 I915 SHEEI 1 01 3 R O T N EV N PAIENH-Illmzs ma SHEEI 2 0f 3 I IIHIIIIIIIIIHII mm wk INVENTOR:FLOYD O GRUVER, JR

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ATTYS PAIENIEOJuu26 ma 3741.229

INVENTOR:

FLOYD O. GRUVER, JR

SAFETY CONTROL VALVE FOR PROPANE CATALYTIC HEATER BACKGROUND Thisinvention relates to a safety control valve, and, more particularly, toa safety control valve for use with propane catalytic heaters.

Catalytic heaters which are fueled by liquid fuel such as white gasolineare well known. These heaters include a catalytic combustion head whichencloses a fuel vapor collection space to which the liquid fuel issupplied by a capillary action wick. The fuel is evaporated from thewick by the heat of the combustion head, and when the combustion on thecombustion head is extinguished, the rate of evaporation of the liquidfuel is reduced to an insignificant, safe level.

Catalytic heaters which are fueled by propane present differentproblems. The propane is generally supplied in pressurized cylinderscontaining gas and liquefied propane. Since the propane gas is suppliedto the heater under pressure, it is desirable that some means beprovided for shutting off the supply of gas if the heater is notoperating. Also, it is desirable to provide some means for metering theamount of fuel being supplied to the heater so that the heat output ofthe heater can be varied as desired.

SUMMARY The invention provides a safety control valve which both metersa desired amount of fuel and performs a safety function by shutting offthe fuel flow when the heater stops operating. The safety shut-off valvecan be manually opened when the heater is to be started to permit fuelto flow to the heater, and the valve will return to a closed positionwhen the manual force is released if the heater has not been started.The safety shut-off valve is operatively connected to an electromagneticpower head which is operatedby a thermocouple, and when the thermocoupleis heated sufficiently by the heater, the safety shut-off will beretained in an open position by the power head. If combustion on thecatalytic combustion head is extinguished, the thermocouple will cool,and the power head will then permit the safety shut-off to close to stopthe flow of fuel. The same operating shaft which opens the safetyshut-off also carries an orifice plate for metering the gas beingsupplied to the combustion head. The orifice plate is provided with aplurality of different sized orifices, each of which will meter the fuelflow at a different rate. Position-indicating means are also carried bythe shaft for indicating when each orifice is properly positioned forgas flow.

DESCRIPTION OF THE DRAWING The invention will be explained inconjunction with an illustrative embodiment shown in the accompanyingdrawing in which FIG. I is a fragmentary perspective view, partiallybroken away, of a propane catalytic heater equipped with the inventivesafety control valve;

FIG. 2 is a front elevational view, partially broken away, of the valve;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is an enlarged view of a portion of FIG. 3;

FIG. 5 is an end view taken along the line 5-5 of FIG. 4;

FIG. 12 is a plan view of the intermediate plate;

FIG. .13 is a plan view of the presser plate; and FIG. 14 is a side viewof the presser plate of FIG. 13.

DESCRIPTION OF SPECIFIC EMBODIMENT Referring now to FIG. 1, the numeraldesignates generally a catalytic heater designed for use withpressurized cylinders of liquefied propane. The heater includes acatalytic combustion head 21 mounted in an outer casing 22 and a fuelcontrol valve 23.

The fuel control valve is mounted within the casing 22 and may beoperated by a control knob 24 on the outside of the casing which can beused to switch the control valve to a variety of positions, for example,low, medium, high and start. The control valve is supplied with fuelthrough a fuel hose 25 which is connected to a suitable source of LP.gas, such as a conventional throw-away cylinder, and the valve suppliesfuel to the combustion head through a tube 26. The thermocouple 27 isoperatively connected to the control valve and extends upwardly in frontof the combustion heater for sensing'the operation of the heater.

Referring now to FIGS; 2 and 3, the safety control valve is seen to havea generally L-shaped body or casing 28 which includes an elongatedgenerally cylindrical safety portion 29 and a generally cylindricalcontrol portion 30 extending generally perpendicularly from the safetyportion. The safety portion includes a central main bore 31, and a pairof radially reduced bores 32 and 33 which extend axially toward thecontrol portion of the valve. The control portion also includes acentral bore 34, and the central bore 34 and the bore 33 communicatethrough an inlet bore 35 having a generally rectangular cross section.

The safety portion of the casing includes an upwardly extendinginternally threaded coupler projection 37, and a fuel passage 38 extendsthrough the coupler projection to the main bore 31. A coupling fitting39 is threadedly engaged with the projection 37 and serves to connectthe fuel supply hose 25 to the valve. As will be explained in detailhereinafter, when the valve is in an open position, fuel can flowthrough the hose 25 and the fuel passage 38 into the main central bore31 of the safety portion of the valve and then through the bores 32,33,and 35 into the central bore 34 of the control portion of the valve. Thefuel then flows through a first outlet bore 40 which extends'parallel tothe axis of the bore 34 but which is offset therefrom and a secondoutlet bore 41 which extends generally vertically upwardly. The upperend of the outlet bore 41 is internally threaded for engagement with acoupling fitting 42 connected to the fuel supply tube 26.

The amount of fuel flowing from the bore 34 of the control portion tothe outlet bore 40 is metered by a circular orifice plate 44 which ismounted for rotation on an elongated control shaft 45. The bore 34 isclosed by a cap 46 which is threadedly engaged with internal threadswithin the bore, and the cap includes a central bore 47 of circularcross section. The operating shaft 45 includes a generally cylindricalportion 450 which has a diameter slightly less than the diameter of thebore 47 and which is rotatably supported therein and a generallyrectangular portion 45b (FIG. 8).

As can be seen best in FIGS. 4 and 7, the orifice plate 44 is providedwith four openings 48, 49, 50 and 51 which are disposed arcuately aroundthe center of the plate. The opening 48 is seen to include a majorportion 48a of relatively constant diameter which extends through mostof the thickness'of the orifice plate and terminates in an orifice 48bsized to permit a desired amount of gas flow therethrough. The otheropenings 49 and 50 may include similarly sized major portions,

. but each of the openings terminates in a different size orifice toprovide varying rates of gas flow depending upon which opening isaligned with the outlet bore 40. An annular enlargement 52 is providedaround the outlet opening and receives a resilient and compressibleO-ring 53 which sealingly engages the orifice plate.

The orifice plate is provided with a generally rectangular centralopening 54 which receives the square portion 45b of the control shaftand an enlarged circular counterbore 55. The rear end of the controlshaft which is inserted through the orifice plate terminates in anannular groove 56 and an end cap portion 57, and the shaft is retainedwithin the orifice plate by means of an E-ring 59 which is positioned inthe annular groove.

. The forward end of the shaft 45 extends through the cap 46 and isprovided-with a notch 58. The control knob 24 is received on the outerend of the shaft, and the knob-and the shaft are locked against relativerotation by the notched end 58 which cooperates with a correspondinglyshaped bore in the knob.'The amount of fuel which flows from the bore 34through the outlet bore 40 can therefore be varied by turning the knobto the orifice plate opening of the desired size with the O- ring 53.

Means for indicating the position of the openings in the orifice plateare provided in the form of three plates 60, 61 and 62, and a coilspring 63. The positionindicating plate 60 is generally circular and hasan outside diameter approximately the same as the inside diameter of thebore 34. The plate is provided with a central opening 64 large enough topermit rotation of the square portion 45b of the shaft therewithin, theplate being secured against rotation by an abutment 65 (FIG. 8) whichextends inwardly from the wall of the casing and is received in acorrespondingly shaped notch 66 in the plate. Four generallyhemispherical pockets or embossments 67, 68, 69 and 70 are formed in theplate 60 and open toward the orifice plate 44.

The intermediate plate 61 includes a generally circular portion 72 (FIG.12) and a radially outwardly extending tongue portion 73. The circularportion is provided with-a generally rectangular central opening 74sized to receive the square shaft portion 45b, and the tongue portion isprovided with a circular opening 75 wardly extending tongue portion 78.A tang or tab 79 extends from the tongue portion 78 generallyperpendicularly to the plane of the plate.

The position-indicating plate 60 is retained on the square shaft portionby an E-ring 81 which is received in an annular groove 82 between therectangular shaft portion 45b and the circular shaft portion 45a. Thepresser plate 62 and the intermediate plate 61 are resiliently biasedagainst the position-indicating plate by the coil spring 63, and a ballbearing 83 (FIG. 6) is positioned in the opening in the intermediateplate 61. The diameter of the ball bearing is greater than the thicknessof the intermediate plate, and the ball bearing is therefore urgedagainst the plate 60 by the presser plate 62. As the plates 61 and 62rotate with the shaft relative to the position-indicating plate 60, theball bearing is moved arcuately along the surface of the plate 60 untilit reaches one of the pockets 67-70. The ball bearing is then forcedinto the pocket, providing both an audible click and a restraining forceagainst further rotation which can be felt by the operator turning theknob. The pockets 68-70 are located relative to the openings 48-50 inthe orifice plate to permit the ball to be received in one of thepockets each time one of the openings in the orifice plate is alignedwith the O-ring 53.

The fourth pocket 67 is for indicating the off position, and when theball is received in this pocket, an imperforate portion of the orificeplate engages the O-ring 53 to seal the outlet opening.

The fourth opening 51 in the orifice plate isaligned with the O-ring 53when the control shaft 45 is turned to the start position as will beexplained more fully hereinafter, and the alignment of this opening withthe O-ring need not be indicated by the indicating means.

Since the pockets are generally hemispherical in shape, the ball can becammed out of a pocket by applying a torque on the shaft sufficient toovercome the bias of the spring 63 which acts on the ball.

The embossments 67-70 in the position-indicating plate 60 engage awasher 85 (FIG. 3) which is received in an annular groove 86, and thewasher in turn engages a compressible and resilient O-ring 87 which ispositioned in annular groove 88. The spring 63 presses the washer 85into engagement with the O-ring 87 to compress the O-ring into sealingengagement with the shaft 45 and the casing and also presses the orificeplate 44 into sealing engagement with the O-ring 53.

The control portion of the valve will be explained with reference toFIG. 2. The interior of the casing 28 includes a circular rim or valveseat 90 which extends axially with respect to the fuel inlet bore 32. Avalve closure member 91 is resiliently biased against the valve seat bya helical coil spring 92, and the particular valve closure memberillustrated includes a compressible and resilient rubber disc 93 and arelatively rigid backup disc 94. The valve closure member is carried bya shaft 95 which extends-into an electromagnetic power head 96 which isthreadedly received by the open end 97 of the casing.

The two wires 27a and 27b which form the thermocouple 27 are connectedto the power head 96 for supplying current thereto. The power head isconventional and a detailed description thereof is believed unnecessary.One particular power head that has been used is available from GeneralControls of Glendale, Calif. The electromagnetic means of the power headis selected to hold the shaft 95 in an open position in which the valveclosure member is spaced from the valve seat 90 when a predeterminedamount of current is supplied to the power head by the thermocouple byvirtue of the heat output from the catalytic combustion head and torelease the shaft when the current drops below a certain minimum.

Means for manually moving the valve closure member to an open positionis provided in the form of an elongated rod 99 which is slidablyreceived in the bores 33 and 35 of the casing. The rod is generallycircular in cross section and is sized to be slidably supported by thesquare bore 35 (FIG. 3), and the other end of the rod is slidablyreceived by a central opening in a lock washer 100 (FIG. The lock washer100 includes a plurality of radially extending projections 101 whichfrictionally engage the wall of the bore 32, and the washer is pressfitted against the shoulder 102 which joins the bores 32 and 33. Thediameter of the circular outer periphery 104 of the washer is less thanthe diameter of the bore 33 to permit gas to flow between theprojections 101 into the bore 33.

A return spring 105 is carried by the rod 99 between the washer 100 andan abutment 106, which can be conveniently provided by an E-ringreceived by an annular groove in the rod. The return spring 105resiliently biases the rod to the left as viewed in FIG. 2 away from thevalve closure member 94, and a stop member 107, which may also be anE-ring received by an annular groove adjacent the end of the rod, ispositioned outwardly of the washer 100.

Referring to FIGS. 8 and 9, the end 79a of the rod 99 is rounded andextends through the bore 35 into the bore 34 a sufficient distance to beengaged by the tang 79 on the presser plate 62 when the shaft 45 isrotated clockwise. The tang is inclined at about 45 from the axis of therod when the rod is contacted, and the inclined surface of the tangpresses the rod toward the valve closure member 91 to unseat the valveclosure member from the valve seat. When the shaft has been rotated toopen the valve 90, the orifice 51 in the orifice plate will have beenrotated into alignment with the O-ring 53 and the outlet bore 40. Fuelwill thereby be permitted to flow from the fuel hose 25 through the fueltube 26 to the combustion head.

When sufficient fuel has been supplied to the com,- bustion head, theheater can be ignited. The control shaft is manually held in the startposition until the thermocouple is heated sufficiently to provide enoughcurrent to the power head to magnetically hold the valve closure memberaway from the valve seat. If the control knob is released before thisminimum amount of current is supplied to the power head, the spring 92will return the valve closure member to the valve seat to shut off theflow of fuel. The spring 105 which is ensleeved on the rod 99 will alsoreturn the rod to its original position and rotate the shaftcounterclockwise as viewed in FIG. 9. It is advantageous to position theposition-indicating pocket 70 relative to the rod 99 so that the ballbearing 83 is positioned in the pocket 70 by the return of the rod. Thehigh fuel flow opening 50 through the orifice plate will then be alignedwith the outlet bore 40, but fuel flow will be stopped by the valveclosure member 91.

if the thermocouple is heated sufficiently before the control shaft isreleased from the start position, the power head will retain the valveclosure member in an open position, and the rod 59 will rotate the shaftto the high fuel flow position in which the ball bearing is positionedin the pocket 70. The operator can then leave the control shaft in thehigh fuel flow position or rotate the shaft to the medium or lowposition.

If for some reason combustion on the combustion head is extinguished,the thermocouple will cool, and the current being supplied to the powerhead will eventually fall below the minimum required to hold the valveclosure member open. The valve closure member will therefore'return tothe closed position, and the flow of fuel will be shut off before adangerous amount of gas can accumulate.

If the control shaft is manually turned to the off position, the orificeplate will immediately block fuel flow to the outlet bore 40, and theheater will be extinguished. As the thermocouple cools, the valveclosure element will also return to the closed position. Accordingly,even if the control shaft is later rotated away from the off position,fuel will not flow.

Although the openings 48-50 in the orifice plate are sized to providelow, medium, and high fuel flow, respectively, the opening 51, throughwhich fuel flows when the control shaft is in the start position, can bethe same size as one of the other openings or can be larger if even morefuel flow is desired to start the heater.

While inthe foregoing specification, a detailed description of aspecific embodiment of the invention was set forth for the purposeofillustration, it is to be understood that many of the details hereingiven may be varied considerably by those skilled in the art withoutdeparting from the spirit and the scope of the invention. I claim:

1. A fuel control valve comprising a casing having a fuel inlet port anda fuel outlet port, a shaft rotatably mounted within the casing, anorifice plate mounted on the shaft for rotation therewith adjacent thefuel outlet port, the orifice plate being provided with a plurality ofdifferent sized openings therethrough, each opening being alignable withthe fuel outlet port as the shaft rotates, a position-indicating plateextending generally parallel with the orifice plate and having a centralopening therethrough rotatably receiving the shaft, theposition-indicating plate being secured against rotation with the shaftby the casing and being provided with a plurality of ball-receivingpockets therein disposed arcuately around the shaft, an intermediateplate mounted on the shaft for rotation therewith between the orificeplate and the position-indicating plate, the intermediate plate havingan opening therethrough spaced from the shaft about the same distance asthe ball-receiving pockets, a ball positioned in the opening in theintermediate plate, and having a diameter greater than the thickness ofthe intermediate plate, a presser plate mounted on the shaft between theintermediate plate and the orifice plate, a coiled spring ensleeved onthe shaft between the orifice plate and the presser plate and biasingthe presser plate toward the intermediate plate to force the ballagainst the position-indicating plate and into the ball-receivingpockets as the intermediate plate rotates with respect to thepositionindicating plate.

2. The fuel control valve of claim 1 in which the easing is providedwith a main bore in which the shaft and the plates mounted thereonrotate and an inlet bore extending generally perpendicularly to the axisof the main bore, a rod slidably mounted within the inlet bore, a springbiasing the rod toward the main bore, a valve seat surrounding the inletbore, a valve closure member resiliantly biased against the valve seatfor closing the inlet bore, and abutment means on one of the plateswhich rotates with the shaft, the abutment means being engageable withthe rod as the shaft rotates for moving the rod against the valveclosure member to force the valve closure member away from the valveseat.

3. The fuel control valve of claim 2 including electromagnetic meansoperatively connected to the valve closure member for holding the valveclosure member away from the valve seat when a predetermined minimumelectric current is supplied thereto and for releasing the valve closuremember when sufficient electric current is not supplied thereto.

4. The fuel control valve of claim 2 in which the abutment meanscomprises a tang extending generally perpendicularly from the presserplate away from the intermediate plate.

5. A fuel control valve for a heater comprising a casing having fuelinlet and fuel outlet means, a shaft rotatably mounted within thecasing, a plate mounted on the shaft for rotation therewith adjacent thefuel outlet means, the plate being provided with a plurality ofdifferent sized openings therethrough, each opening being alignable withthe fuel outlet means as the shaft rotates, valve means for opening andclosing the fuel inlet means, electromagnetic means for maintaining thevalve open when the heater is operating, a second plate mounted on theshaft for rotation therewith, the second plate including abutment means,a rod slidably mounted within the casing for axial sliding movementtoward and away from the valve means, the abutment means being rotatableinto engagement with the rod as the shaft rotates to push the rodagainst the valve means to open the valve means, a third plate having acentral opening receiving the shaft, the third plate being provided witha plurality of arcuately disposed ball-receiving pockets therein, and aball yieldably biased against the third plate whereby the ball is forcedsuccessively into and out of the pockets as the ball travels arcuatelyover the third plate to provide position indicating means.

6. The fuel control valve of claim 5 including a fourth plate mounted onthe shaft between the second and third plates, the ball being positionedwithin an opening in the fourth plate and having a diameter greater thanthe thickness of the fourth plate, the third plate being secured againstrotation by the casing, and spring means on the shaft biasing the secondplate toward the fourth plate for urging the ball against the thirdplate.

7. A fuel control valve for a heater comprising a casing having a fuelinlet and fuel outlet means, a shaft rotatably mounted within thecasing, a first plate mounted on the shaft for rotation therewithadjacent the fuel outlet means, the first plate being provided with aplurality of different sized openings therethrough, each opening beingalignable with the fuel outlet means as the shaft rotates, second andthird plates, each of the second and third plates having a centralopening receiving the shaft, the second plate being provided with aplurality of arcuately disposed pockets therein opening toward the thirdplate, one of the second and third plates being rotatable with the shaftand the other of the second and third plates being secured againstrotation with the shaft, spring means within the casing for yieldablybiasing the second and third plates together, and ball means positionedbetween the second and third plates and being yieldably biased againstthe second plate, the ball means being receivable in the pockets as thesecond and third plates rotate relative to each other.

8. A fuel control valve for a heater comprising a casing having a fuelinlet and fuel outlet means, a shaft rotatably mounted within thecasing, a first plate mounted on the shaft for rotation therewithadjacent the fuel outlet means, the first plate being provided with aplurality of different sized openings therethrough, each opening beingalignable with the fuel outlet means as the shaft rotates, second andthird plates, each of the second and third plateshaving a centralopening receiving the shaft, the second plate being provided with aplurality of arcuately disposed pockets therein opening toward the thirdplate, one of the second and third plates being rotatable with the shaftand the other of the second and third plates being secured againstrotation with the shaft, a fourth plate mounted on the shaft forrotation therewith between the second and third plates and having anopening therethrough spaced from the shaft about the same distance asthe pockets of the second plate, and a ball bearing positioned withinthe opening in the fourth plate and between the second and third platesand having a diameter' greater than the thickness of the fourth plate,the ball bearing being yieldably biased against the second plate andbeing receivable in the pockets of the second plate as the second andthird plates rotate relative to each other.

9. The fuel control valve of claim 8 in which the ball bearing isyieldably biased against the second plate by a coil spring ensleeved onthe shaft between the first plate and the second or third plate which'isclosest to the first plate.

1. A fuel control valve comprising a casing having a fuel inlet port anda fuel outlet port, a shaft rotatably mounted within the casing, anorifice plate mounted on the shaft for rotation therewith adjacent thefuel outlet port, the orifice plate being provided with a plurality ofdifferent sized openings therethrough, each opening being alignable withthe fuel outlet port as the shaft rotates, a position-indicating plateextending generally parallel with the orifice plate and having a centralopening therethrough rotatably receiving the shaft, thepositionindicating plate being secured against rotation with the shaftby the casing and being provided with a plurality of ball-receivingpockets therein disposed arcuately around the shaft, an intermediateplate mounted on the shaft for rotation therewith between the orificeplate and the position-indicating plate, the intermediate plate havingan opening therethrough spaced from the shaft about the same distance asthe ball-receiving pockets, a ball positioned in the opening in theintermediate plate, and having a diameter greater than the thickness ofthe intermediate plate, a presser plate mounted on the shaft between theintermediate plate and the orifice plate, a coiled spring ensleeved onthe shaft between the orifice plate and the presser plate and biasingthe presser plate toward the intermediate plate to force the ballagainst the position-indicating plate and into the ball-receivingpockets as the intermediate plate rotates with respect to theposition-indicating plate.
 2. The fuel control valve of claim 1 in whichthe casing is provided with a main bore in which the shaft and theplates mounted thereon rotate and an inlet bore extending generallyperpendicularly to the axis of the main bore, a rod slidably mountedwithin the inlet bore, a spring biasing the rod toward the main bore, avalve seat surrounding the inlet bore, a valve closure memberresiliantly biased against the valve seat for closing the inlet bore,and abutment means on one of the plates which rotates with the shaft,the abutment means being engageable with the rod as the shaft rotatesfor moving the rod against the valve closure member to force the valveclosure member away from the valve seat.
 3. The fuel control valve ofclaim 2 including electromagnetic means operatively connected to thevalve closure member for holding the valve closure member away from thevalve seat when a predetermined minimum electric current is suppliedthereto and for releasing the valve closure member when sufficientelectric current is not supplied thereto.
 4. The fuel control valve ofclaim 2 in which the abutment means comprises a tang extending generallyperpendicularly from the presser plate away from the intermediate plate.5. A fuel control valve for a heater comprising a casing having fuelinlet and fuel outlet means, a shaft rotatably mounted within thecasing, a plate mounted on the shaft for rotation therewith adjacent thefuel outlet means, the plate being provided with a plurality ofdifferent sized openings therethrough, each opening being alignable withthe fuel outlet means as the shaft rotates, valve means for opening andclosing the fuel inlet means, electromagnetic means for maintaining thevalve open when the heater is operating, a second plate mounted on theshaft for rotation therewith, the second plate including abutment means,a rod slidably mounted within the casing for axial sliding movementtoward and away from the valve means, the abutment means being rotatableinto engagement with the rod as the shaft rotates to push the rodagainst the valve means to open the valve means, a third plate having acentral opening receiving the shaft, the third plate being provided witha plurality of arcuately disposed ball-receiving pockets therein, and aball yieldably biased against the third plate whereby the ball is forcedsuccessively into and out of the pockets as the ball travels arcuatelyover the third plate to provide position-indicating means.
 6. The fuelcontrol valve of claim 5 including a fourth plate mounted on the shaftbetween the second and third plates, the ball being positioned within anopening in the fourth plate and having a diameter greater than thethickness of the fourth plate, the third plate being secured againstrotation by the casing, and spring means on the shaft biasing the secondplate toward the fourth plate for urging the ball against the thirdplate.
 7. A fuel control valve for a heater comprising a casing having afuel inlet and fuel outlet means, a shaft rotatably mounted within thecasing, a first plate mounted on the shaft for rotation therewithadjacent the fuel outlet means, the first plate being provided with aplurality of different sized openings therethrough, each opening beingalignable with the fuel outlet means as the shaft rotates, second andthird plates, each of the second and third plates having a centralopening receiving the shaft, the second plate being provided with aplurality of arcuately disposed pockets therein opening toward the thirdplate, one of the second and third plates being rotatable with the shaftand the other of the second and third plates being secured againstrotation with the shaft, spring means within the casing for yieldablybiasing the second and third plates together, and ball means positionedbetween the second and third plates and being yieldably biased againstthe second plate, the ball means being receivable in the pockets as thesecond and third plates rotate relative to each other.
 8. A fuel controlvalve for a heater comprising a casing having a fuel inlet and fueloutlet means, a shaft rotatably mounted within the casing, a first platemounted on the shaft for rotation therewith adjacent the fuel outletmeans, the first plate being provided with a plurality of differentsized openings therethrough, each opening being alignable with the fueloutlet means as the shaft rotates, second and third plates, each of thesecond and third plates having a central opening receiving the shaft,the second plate being provided with a plurality of arcuately disposedpockets therein opening toward the third plate, one of the second andthird plates being rotatable with the shaft and the other of the secondand third plates being secured against rotation with the shaft, a fourthplate mounted on the shaft for rotation therewith between the second andthird plates and having an opening therethrough spaced from the shaftabout the same distance as the pcokets of the second plate, and a ballbearing positioned within the opening in the fourth plate and betweenthe second and third plates and having a diameter greater than thethickness of the fourth plate, the ball bearing being yieldably biasedagainst the second plate and being receivable in the pockets of thesecond plate as the second and third plates rotate relative to eachother.
 9. The fuel control valve of claim 8 in which the ball bearing isyieldably biased against the second plate bY a coil spring ensleeved onthe shaft between the first plate and the second or third plate which isclosest to the first plate.